Image Credit: Vik Nanda / Flickr. This image has been modified.

Vitamin D from Mushrooms, Sun, or Supplements?

Years ago, it was shown that vitamin D isn’t just the sunshine vitamin for us, but for mushrooms as well. You take some mushrooms, put them under a sun lamp for an hour, and they’ll make vitamin D just like we do lounging at the pool.

Unfortunately most mushrooms you buy at the store don’t have any vitamin D because they’re grown in the dark, but now there are sun-bathed varieties on the market that boast significant levels. Some mushrooms grown out in the wild have vitamin D as well, but only about 12% of one’s recommended daily allowance per cup.

Is the vitamin D in mushrooms bioavailable? In 2008 there was a case report of a dark skinned individual living in England in the winter who–like the other 9 out of 10 South Asians living in the UK–was vitamin D deficient. His physician prescribed a vitamin D supplement, but after doing his own research this patient decided to self-treat. He bought a UV bulb from a local hardware shop and proceeded to shine it directly onto 2 cups of regular mushrooms a day before stir-frying and consuming them. He repeated this on a daily basis for 3 months, and indeed his vitamin D levels shot up and he was cured.  So it’s reasonable to assume that such mushrooms may be able to provide a source of vitamin D for those at risk for deficiency. This was just one person though, so further studies were necessary, and finally those studies have been done.

In my 5-min video Is Vitamin D3 Better Than D2? I profile a study entitled Bioavailability of Vitamin D from Ultraviolet Light Irradiated Button Mushrooms in Healthy Adults Deficient in Serum 25-Hydroxyvitamin D: A Randomized Controlled Trial. The mushrooms were compared to vitamin D supplements and placebo, and both the mushrooms and the supplements were equally effective in raising vitamin D levels compared to the placebo.

The type of D made by mushrooms is vitamin D2, which is typically derived from yeast and is the form traditionally prescribed by doctors to cure D deficiency. Most supplements, though, are D3, which is the type found in plants and animals, typically derived from sheep’s wool. Back in 2008 it was established that vitamin D2 was as effective as D3 in maintaining one’s vitamin D levels at standard daily dosing levels. As you can see in the video, whether folks were given D3, D2, or a combo of half D3 and D2, it didn’t seem to matter much in terms of improving vitamin D levels in the bloodstream. But that was 5 years ago–what’s the update? Is vitamin D2 better than vitamin D3? It depends how you take it and what your starting levels are. Watch my video Is Vitamin D3 Better Than D2? for the latest details.

Here are my vitamin D recommendations for those in the northern hemisphere:

  • Below approximately 30° latitude (south of Los Angeles/Dallas/Atlanta/Cairo)
    • 15-30 minutes of midday sun (15 for those with lighter skin; 30 for those with darker skin)
    • or 2,000 IU supplemental vitamin D daily
  • Between 30° latitude (sample cities above) & 40°latitude (Portland/Chicago/Boston/Rome/Beijing)
    • From February through November
      • 15-30 minutes of midday sun (15 for those with lighter skin; 30 for those with darker skin)
      • or 2,000 IU supplemental vitamin D daily
    • From December through January
      • 2,000 IU supplemental vitamin D daily
  • Between 40° latitude (sample cities above) & 50° latitude (Edmonton/London/Berlin/Moscow)
    • From March through October
      • 15-30 minutes of midday sun (15 for those with lighter skin; 30 for those with darker skin)
      • or 2,000 IU supplemental vitamin D daily
    • From November through February
      • 2,000 IU supplemental vitamin D daily
  • Above approximately 50° latitude (north of Edmonton/London/Berlin/Moscow)
    • From April through September (or even briefer above 60°latitude (Anchorage/Stockholm)
      • 15-30 minutes of midday sun (15 for those with lighter skin; 30 for those with darker skin)
      • or 2,000 IU supplemental vitamin D daily
    • From October through March (or even longer above 60°latitude (Anchorage/Stockholm)
      • 2,000 IU supplemental vitamin D daily

That’s not what the Institute of Medicine says though. I justify my recommendation in this video series:

What about tanning beds? See Vitamin D Pills vs. Tanning Beds.

I also recommend to Take Vitamin D Supplements With Meals.

I still think people should eat mushrooms though! For starters, see:

-Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

27 responses to “Vitamin D from Mushrooms, Sun, or Supplements?

Comment Etiquette

On, you'll find a vibrant community of nutrition enthusiasts, health professionals, and many knowledgeable users seeking to discover the healthiest diet to eat for themselves and their families. As always, our goal is to foster conversations that are insightful, engaging, and most of all, helpful – from the nutrition beginners to the experts in our community.

To do this we need your help, so here are some basic guidelines to get you started.

The Short List

To help maintain and foster a welcoming atmosphere in our comments, please refrain from rude comments, name-calling, and responding to posts that break the rules (see our full Community Guidelines for more details). We will remove any posts in violation of our rules when we see it, which will, unfortunately, include any nicer comments that may have been made in response.

Be respectful and help out our staff and volunteer health supporters by actively not replying to comments that are breaking the rules. Instead, please flag or report them by submitting a ticket to our help desk. is made up of an incredible staff and many dedicated volunteers that work hard to ensure that the comments section runs smoothly and we spend a great deal of time reading comments from our community members.

Have a correction or suggestion for video or blog? Please contact us to let us know. Submitting a correction this way will result in a quicker fix than commenting on a thread with a suggestion or correction.

View the Full Community Guidelines

  1. Hi Doc,

    For those of us with Sarcoidosis and that have Vitamin D dysregulation, supplementing could be a big problem – as I am now finding out. Symptoms get worse.


  2. Literature and clinical experience demonstrate that vitamins D2 and D3 raise serum levels equally well. However, with D2 levels quickly drop once supplementation ceases. Levels raised with Vitamin D3 supplementation remain in the normal range longer. In addition vitamins D2 and D3 have *slightly* different metabolic pathway end points and D2 binds less well to vitamin D receptors. On balance, I recommend D3 to my patients. If they must use D2 (for financial reasons — it’s covered by insurance since it’s a drug) I switch them to lower dose D3 after the D2 course and emphasize the need for them to keep taking it with their largest meal of the day to facilitate absorption (see Cleveland Clinic osteoarthritis clinic study published ~2 years ago). During the sunny season I recommend limb exposure to sunlight (hat/sunscreen for more chronically exposed face and shoulders).

  3. Midday sun is the strongest/most dangerous. Wouldn’t it be safer to get exposure earlier/later in the day, maybe for longer then, or is the sun not producing the required spectrum at those times? You did not specify how many days/week or did you mean daily?

    1. I second this! I share Dr. Greger’s nutrition recommendations with lots of people. I understand all of them except the DHA oil one. It just doesn’t seem like there is enough evidence to support such a recommendation. I was taken by a talk I saw not too long ago by (I think) Dr. McDougall who said something like: it is true that our bodies don’t convert much omega 3 from flaxseed and other plant sources, but it does make all that we need. *If* that is so, then I don’t understand Dr. Greger’s recommendation.

      Thanks BPCveg for being the first to voice my interest too.

      1. Dr. Gregor’s recommendation to my knowledge is, take DHA as an insurance policy if you have the means, and if one is pregnant he then highly recommends supplementation. A lot of it depends on how good one’s diet is. If one is consuming a lot of Omega 6 rich foods, like peanut butter and nuts and such, then they would most likely benefit from DHA oil in their diet. But if one had an ideal diet, with a 1 -1 ratio of 6 and 3 omegas, then DHA oil would probably be unnecessary. But in the case of pregnancy, probably best to err on the side of caution and take the oil no matter how good your diet is.

  4. Hi!
    I live in France and I’d like to know if you could recommend me a website where I can purchase safe, good Vitamin D supplements?
    Thanks in advance,

  5. I don’t like to get midday sun, but morning and evening because the sun is too burning during the midday in summer, you don’t really say how long for non-midday sun exposure.

    1. The midday sun is recommended because the atmosphere at other times will block the rays that we need to make Vit D. The sunburn rays will get through though so morning and evening sun will only burn not make D for us.

  6. Unfortunately most mushrooms you buy at the store don’t have any vitamin D Some mushrooms grown out in the wild have vitamin D as well, but only about 12% of one’s recommended daily allowance per cup. i am unable to understand the fact that —-You can only make vitamin D when your shadow is shorter than you are…is it true ?


    1. DietKart: “i am unable to understand the fact that —-You can only make vitamin D when your shadow is shorter than you are…is it true ?”

      I am guessing that this bit of advice came from the issue that you can only make enough vitamin D to satisfy your needs in say 20 minutes of time if you are in the noon day sun. (At which point you would have a shorter shadow.)

      There are several videos on this site about vitamin D. Dr. Greger also addresses how much sun and at what time of day for creating vitamin D by where you live in the world on the following page:

    1. I think regularly exposed areas are not as sensitive. So hands and face absorb vitamin D but perhaps not as much as bare back and chest. Surface area matters.

  7. Do you think that Vitamin D3 containing 1000Iu COLECALCIFEROL is toxic or not . shall i take it or not thanks zouhair najjar {FIORINO}.

  8. do you think Doctor that medicine DEPO-PROVERA 150mg Medroxyprogesterone Acetate has any negative side effect on Vitamin D3 and may cause deficciency

  9. Hi there!! I calculated myself to be a 20-minute midday sun person. So, A. Do the 20 minutes have to be concurrent? B. Which hours are considered to be midday (11am – 2pm?) C. If I’m out on the golf course for 3 midday hours, do I incur 18,000 IUs of vitaminD which would make me good for 9 days?
    Any input would be greatly appreciated.

  10. The vegan D3 supplement I’ve been taking says it is derived from a lichen, but which species is typically used? Native Americans ate lots of lichen, e.g., Alectoria and Usnea spp. I would rather eat the whole food than the supplement, but I cannot find any info on specific lichen species and D3 levels. Can you?

  11. I’m really interested in the idea of buying a UVB lamp and shining it on my mushrooms just to get extra D, especially during those tough winter months. It really worked for the guy in England that Dr. Gregor referenced. Does anyone do this already? I was looking at some fixtures and UVB bulbs that are used for pets like lizards. I wonder if that would work?

  12. nc54: I say yes! I bought this UVB lizard light and fixture on Amazon:

    Reptile T5HO 12″ Standard Fixture & Reflector

    Zoo Med 26396 Reptisun 15W 10.0 T5-Ho Uvb Fluorescent Lamp, 12″

    Note: You can purchase cheaper fixtures and lights. I wanted something extremely small and compact, so I was willing to pay extra for it.

    I shine it right over my mushrooms at a distance of about 4-5″ for five minutes. Super easy!

    My question: the guy in England irradiated his mushrooms and ate them immediately with some fat (he stir-fried them, which seems like a good move since Vitamin D is fat-soluble).

    However, the research below makes it appear that it would be helpful to irradiate, then WAIT for the Vitamin D to be converted more. After irradiating, should I wait 12 hours to eat the mushrooms?
    “Photobiology of vitamin D in mushrooms and its bioavailability in humans”

    “A 96 h time course was conducted to examine the conversion of previtamin D2 to vitamin D2 in UV irradiated white button mushrooms…Immediately after irradiation and at various times, the samples were chromatographed to determine the percent conversion of previtamin D2 and vitamin D2…

    There was a time dependent increase in the amount of vitamin D2. At 6 h after irradiation, 24% of the previtamin D2 in white button mushroom had converted to vitamin D2…

    After 11.5 h, 50% of the previtamin D2 present in white button mushrooms had converted to vitamin D2…”

    Irradiate and wait, or just irradiate?

Leave a Reply

Your email address will not be published. Required fields are marked *

Pin It on Pinterest

Share This